With all the tube and torrent sites being around, a site needs more than just a lot of content.
You have to offer something the surfer can't get from the tube or torrent sites.
Cams, interaction, updates, exclusivity, fun, reality, amateurs.
These are my 2008 pointers. We trying to combine all these in one project and so far it's looking really good.
pocketkangaroo has some very good points with the liveshows and requests.
You need retention. So your surfer must have something to come back to.
And since your exclusively shot movies end up on torrents and tube sites in a matter of days, you either need to update ALL THE FUCKING TIME or offer something else/more.
Camshows, interaction with the models, polls, a forum, and so on.
It is important to surf the web from a surfers POV every now and then.
Set some targets: Need porn now. And see where it takes you. It's just scary

And keep an eye on the things that are hard to find. Those are your opportunities....